Third Treaty of San Ildefonso

The Third Treaty of San Ildefonso was a treaty between the French Consulate and Spain that was signed on 1 October 1800, with Spain retroceding French Louisiana to France in exchange for Infante Luis becoming King Louis I of Etruria. Spain effectively gained control of Tuscany in Italy, but it lost a territory that was one-hundred times larger than Tuscany. The treaty also affirmed the alliance between First Consul Napoleon Bonaparte and King Carlos IV of Spain.